DESCRIPTION: (Applicant's Abstract) Therapy for HIV infection has evolved dramatically in the past year; we are in an era in which it may be possible to suppress the virus for an indefinite time. Yet, many patients may not be able to tolerate or adhere to these complex drug regimens, and, to date, much of our evidence regarding the effectiveness of these drugs is based on short-term studies. Supported by a 5-year RO1 from AHCPR, we developed a longitudinal database of HIV-infected patients receiving care in an urban HIV center. This database was designed to capture comprehensive information on the treatment and subsequent clinical progression of HIV infection over many years of follow-up. The methodology of data collection, automation, and analysis is well-established and the database currently has over 7000 person-years of follow-up time. At enrollment, approximately half the patients have early asymptomatic infection and half with symptomatic disease or AIDS. Our patients are predominately of minority race and poor, with a high proportion of women (30%). When our database was started in 1990, illicit drug users comprised 25% of our patient population. Illicit drug use is now the most common risk factor for HIV transmission (>50% of all new enrollees) with active drug use a continuing problem in the majority of these patients. It is appropriate for us to now change the focus of our research effort to assessing the utilization and effectiveness of the new antiretroviral drugs in the illicit drug user. Based on preliminary analyses, we hypothesize that in this new therapeutic era, illicit drug users may be less likely to receive or maintain use of HIV therapy and may have a higher rate of failure with poorer outcomes than non-drug users. Our specific aims are to compare illicit drug users with non-drug users as to 1) utilization patterns of potent antiretroviral therapy, 2) long-term effectiveness of potent antiretroviral therapy in reducing HIV-1 RNA, increasing CD4 count, slowing progression of HIV disease and prolonging survival, 3) utilization and effectiveness of prophylactic therapy for opportunistic infection. We are building upon an established database with an experienced and productive research team and are well-positioned to compare drug users and non-drug users in regard to our aims, contributing to an improved understanding of HIV disease in the illicit drug user in clinical practice over the next five years.